statsmodels.genmod.generalized_estimating_equations.GEE.fit

GEE.fit(maxiter=60, ctol=1e-06, start_params=None, params_niter=1, first_dep_update=0, cov_type='robust', ddof_scale=None, scaling_factor=1.0)

Fits a marginal regression model using generalized estimating equations (GEE).

Parameters:

• maxiter (integer) – The maximum number of iterations
• ctol (float) – The convergence criterion for stopping the Gauss-Seidel iterations
• start_params (array-like) – A vector of starting values for the regression coefficients. If None, a default is chosen.
• params_niter (integer) – The number of Gauss-Seidel updates of the mean structure parameters that take place prior to each update of the dependence structure.
• first_dep_update (integer) – No dependence structure updates occur before this iteration number.
• cov_type (string) – One of “robust”, “naive”, or “bias_reduced”.
• ddof_scale (scalar or None) – The scale parameter is estimated as the sum of squared Pearson residuals divided by N - ddof_scale, where N is the total sample size. If ddof_scale is None, the number of covariates (including an intercept if present) is used.
• scaling_factor (scalar) – The estimated covariance of the parameter estimates is scaled by this value. Default is 1, Stata uses N / (N - g), where N is the total sample size and g is the average group size.

Returns:

Return type:

An instance of the GEEResults class or subclass

Notes

If convergence difficulties occur, increase the values of first_dep_update and/or params_niter. Setting first_dep_update to a greater value (e.g. ~10-20) causes the algorithm to move close to the GLM solution before attempting to identify the dependence structure.

For the Gaussian family, there is no benefit to setting params_niter to a value greater than 1, since the mean structure parameters converge in one step.